Synthesis and Properties of Linear, Cyclic, and Cage Compounds Consisting of Benzodisilacyclobutene Units

本课题通过苯并[1，2：4，5]双（1，1，2，2-四甲基-1，2-二硅杂环丁-3-烯）与钯配合物的复分解反应，合成了大环带状环番化合物和苯环1，2，4，5-位通过乙硅烷链连接的线型同系物，并对其结构、包合物的形成和电子态进行了研究。目前已分离出线性二聚体到五聚体以及环状四聚体和五聚体，X射线衍射分析表明，环状四聚体具有带状菱面体结构，空腔直径为7.3 nm，但不含溶剂分子。环状五聚体和环状四聚体八氧化物分别在直径为11.9和10.4 μ m的空腔中包含苯分子。苯分子以平行于环蕃环的方式被包括在内。虽然苯分子在空气中很容易从环状五聚体的相对较大的空腔中逃逸，但环状四聚体八氧化物紧紧地抓住苯分子，并且在空气中和减压下不会释放它。线性三聚体具有由1，2，4，5-四硅基苯单元组成的锯齿形结构，并且在锯齿形结构形成的空间中包含两个四氢呋喃分子。这种包合方式是罕见的，被认为是双钳包合型，这些化合物的紫外光谱随着1，2，4，5-四硅基苯单元数目的增加而红移，消光系数增加。这些结果表明，硅-硅σ轨道与苯环π轨道之间的σ-π共轭扩展到整个分子。

In this project, the belt-shaped large ring cyclophanes and the linear homologs in which the 1,2,4,5-positions of benzene rings are connected by disilane chains were synthesized, and their structures, the formation of inclusion compounds, and the electronic states were investigated.These compounds were synthesized by the metathesis of benzo[1,2:4,5]bis(1,1,2,2-tetramethyl-1,2-disilacyclobut-3-ene) with the palladium complex. The linear dimer to pentamer and the cyclic tetramer and pentamer have been isolated so far.The X-ray analysis showed that the cyclic tetramer has the belt-shaped rhombohedral structure with a cavity of 7.3 Å diameter, but it does not include a solvent molecule. The cyclic pentamer and the cyclic tetramer octaoxide include a benzene molecule in the cavity of 11.9 and 10.4 Å diameter, respectively. The benzene molecule is included in the parallel manner to the cyclophane ring. Although the benzene molecule easily escapes from the relatively large cavity of the cyclic pentamer in the air, the cyclic tetramer octaoxide holds the benzene molecule tightly and does not release it in the air and under reduced pressure. Therefore, benzene can be reversibly or irreversibly included by controlling the cavity size.The linear trimer has the zigzag structure consisting of 1,2,4,5-tetrasilylbenzene units and includes two tetrahydrofuran molecules in the space formed by the zigzag structure. This inclusion way is rare and is regarded as the double-tweezers type.The UV spectra of these compounds show the bathochromic shift and the increment of the extinction coefficient as the number of the 1,2,4,5-tetrasilylbenzene units increases. These results indicate that the σ-π conjugation between the silicon-silicon σ orbitals and the π orbitals of the benzene rings is extended all over the molecules.